The field of the invention is cutters and the invention relates more particularly to cutters of the type used to open boxes and bags. Such cutters are widely used in fast food restaurants, grocery stores and various establishments where shipments are made in boxes or bags which must be opened to remove the contents for sale or other processing.
One consideration for the use of such cutters in restaurants is to provide a cutter from which the blade is not removable. In the past, substantial liability has occurred from the inadvertent transfer of a blade from a cutter into the food. Even though such occurrence is extremely rare, it is conceivable. Because it is conceivable, there are persons who will put blades in the food and attempt to collect money from the owner of the business.
It is also important that the blades be guarded to reduce the possible of accidental cuts to employees. Various designs of safety cutters have been devised which typically utilize pivoting guards. One such cutter is shown in U.S. Pat. No. 3,781,988 which shows a pivoting guard. A spring is attached to the guard in such a way that it may be moved over center to hold the guard away from the blade.
Another style of safety guard is shown in U.S. Pat. No. 4,091,537 where a spring loaded blade guard moves under the cutting edge of a blade. Only when the blade guard is retracted is the blade exposed.
A cutter with a pivoting blade guard is shown in U.S. Pat. No. 4,675,996. The guard pivots up to expose the blade for cutting.
Another pivoting guard design is shown in U.S. Pat. Nos. 5,522,135 and 5,697,157. In these cutters, the guard is pivoted behind the blade and retracts when the cutter is pulled along a surface to be cut.
Most of the prior art guards are released by moving the cutter along a surface to be cut. The guards have no means for being locked in an extended position and, thus, the blade can be inadvertently exposed when it is not intended to be exposed. Furthermore, all of the blades in the above-discussed patents are removable and provide the possibility of ending up, for instance, in a final food product.